How do I calculate the volume of a pool with a sloped floor?

Use the sloped (variable depth) mode. A pool that gets deeper at one end is treated as a rectangle whose depth is the average of the shallow end and the deep end — so a 3 ft shallow end and an 8 ft deep end average to 5.5 ft, and the tool multiplies length × width × 5.5. This averaging works for a steady, even slope. If your pool has a flat shallow shelf and then a sharp drop into a deep well, the simple average slightly overestimates; for those, split the pool into two boxes mentally and add them. The tool shows the exact average depth it used so you can sanity-check it against your measurements.

How do I convert between gallons, liters, and cubic meters?

You do not have to — the tool shows all three at once from a single set of dimensions. For the record: 1 cubic meter is exactly 1,000 liters and about 264.17 US gallons, and 1 US gallon is about 3.785 liters. So a 50,000-liter pool is 50 cubic meters and roughly 13,210 US gallons. Note these are US liquid gallons, not UK (imperial) gallons; an imperial gallon is about 4.546 liters, so if you are in the UK divide the US-gallon figure by about 1.20.

What is the formula for a round (circular) pool?

Volume = π × radius² × depth, where the radius is half the diameter. So a round pool 18 ft across and 5 ft deep is π × 9² × 5 = π × 81 × 5 ≈ 1,272 cubic feet, which the tool then converts to about 9,518 US gallons. A common mistake is to square the diameter instead of the radius — that overstates the volume by 4×. Just measure the full width across the center (the diameter) and let the tool halve it for you.

Why is the measured volume a little different from the real water level?

Two reasons. First, you rarely fill a pool to the absolute brim — water usually sits a few inches below the coping, so the actual water volume is a touch less than the full structural depth you measured. Second, most pools are not perfect geometric solids: rounded corners, a beach entry, steps, and benches all displace water the formula does not know about. Treat the result as accurate to within a few percent — plenty precise for dosing chemicals or sizing a heater, but expect a real fill to land slightly under the calculated number.

How much chlorine does my pool need?

The maintenance panel gives a rough starting dose: about 10.7 fluid ounces of 12.5% liquid chlorine per 10,000 gallons raises free chlorine by roughly 1 ppm. That is a reference, not a prescription — always test your water first and dose toward your target (typically 1–3 ppm free chlorine). Chlorine demand rises with heat, sunlight, and bather load, and tablet or granular products have different strengths, so use this number to ballpark a purchase, then let a test kit drive the actual dose.

Dose chlorine for a season opening

You are opening the pool in spring and the water has gone green over winter. Measure your 32 × 16 ft rectangle with a 5 ft average depth, read back about 19,150 gallons, and use the maintenance panel to ballpark the liquid chlorine for a shock dose. You test first, then dose toward target rather than guessing by the capful.

Estimate the water bill for filling a new pool

A contractor just finished your 18 ft round pool. You read ~9,500 gallons from the round mode, divide by 748 gallons per CCF, and multiply by your water utility's per-CCF rate to estimate the fill cost before you turn on the hose for two days straight.

Size a pool heater before buying

You want the pool a comfortable 86°F and the spec sheets are quoted in BTU. Get your gallons here, use the heat-time reference to see roughly how long a 100k-BTU unit takes to raise the water 10°F, and decide whether to step up to a bigger heater or a heat pump.

Plan a backyard water feature or koi pond

You are a gardener building an oval reflecting pond. The oval mode gives the liters so you can size the pump (turnover should cycle the whole volume every 1–2 hours) and estimate how much dechlorinator the fill needs before any fish go in.

Convert a European pool spec to gallons

A pool listing from overseas quotes "48 m³". Switch the unit toggle to meters, type the dimensions, and read the US-gallon figure so you can compare it against domestic pumps, covers, and chemicals sold by the gallon.

Pool Volume Calculator — gallons, liters & cubic meters for any pool shape

Find how many gallons (and liters and cubic meters) your pool holds — rectangle, round, oval, or sloped floor — in feet or meters

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Units:

Length (Feet)

Width (Feet)

Average depth (Feet)

Pool water volume

19,150US gallons

72,491Liters

72.5Cubic meters

Maintenance reference

Liquid chlorine (12.5%) to add ~1 ppm20.5 fl oz
Heat 10°F with a 100k-BTU heater16.0 hr
Refill from empty (garden hose)35.5 hr

Rough estimates only — real values depend on your heater, pump, and chemical strength.

What this tool does

Tell it the shape of your pool and the dimensions, and this calculator returns the water volume three ways at once: US gallons, liters, and cubic meters. It keeps four pool shapes separate because the math is genuinely different for each — a round pool is π·r²·depth, not "diameter squared", and an oval has its own elliptical formula — so you do not have to remember which one to apply. The sloped-floor mode averages your shallow-end and deep-end depths for you, which is the number most people forget to compute. Enter dimensions in feet or meters; the unit toggle re-runs the whole conversion instantly. Once you know the gallons, the maintenance panel gives rough references for everyday pool chores: roughly how much liquid chlorine raises free chlorine by 1 ppm, how long a typical gas heater needs to warm the water 10°F, and how many hours a garden hose takes to fill the pool from empty. Those figures are starting points, not guarantees — real numbers depend on your heater, pump, and chemical strength, and the tool labels them that way. Everything runs in your browser; nothing about your pool is sent anywhere, and the share link reproduces the exact pool you typed.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 11 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Operations; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Pool Volume Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Dose chlorine for a season opening
You are opening the pool in spring and the water has gone green over winter. Measure your 32 × 16 ft rectangle with a 5 ft average depth, read back about 19,150 gallons, and use the maintenance panel to ballpark the liquid chlorine for a shock dose. You test first, then dose toward target rather than guessing by the capful.
Estimate the water bill for filling a new pool
A contractor just finished your 18 ft round pool. You read ~9,500 gallons from the round mode, divide by 748 gallons per CCF, and multiply by your water utility's per-CCF rate to estimate the fill cost before you turn on the hose for two days straight.
Size a pool heater before buying
You want the pool a comfortable 86°F and the spec sheets are quoted in BTU. Get your gallons here, use the heat-time reference to see roughly how long a 100k-BTU unit takes to raise the water 10°F, and decide whether to step up to a bigger heater or a heat pump.
Plan a backyard water feature or koi pond
You are a gardener building an oval reflecting pond. The oval mode gives the liters so you can size the pump (turnover should cycle the whole volume every 1–2 hours) and estimate how much dechlorinator the fill needs before any fish go in.
Convert a European pool spec to gallons
A pool listing from overseas quotes "48 m³". Switch the unit toggle to meters, type the dimensions, and read the US-gallon figure so you can compare it against domestic pumps, covers, and chemicals sold by the gallon.

Common pitfalls

Squaring the diameter instead of the radius on a round pool. Volume uses π·r²·depth, and the radius is half the diameter — squaring the full diameter overstates the water by 4×. Enter the full width and let the tool halve it.
Forgetting to average a sloped floor. People plug the deep-end depth into a rectangle formula and overstate the volume badly. Use the variable-depth mode so the shallow and deep ends are averaged correctly.
Mixing up US and imperial gallons. The tool reports US liquid gallons; an imperial (UK) gallon is about 20% larger, so a US-gallon figure looks bigger than the imperial count for the same water.

Privacy

Every calculation — the geometry, the unit conversions, and the maintenance estimates — is plain JavaScript that runs inside your browser tab. The dimensions of your pool never leave the page, there is no logging, and there is no external API call. The one thing to know: the shareable URL encodes your shape, dimensions, and unit in the query string (e.g. ?s=round&d=18&h=5), so if you paste a share link somewhere, the destination server's access log will record those numbers. Pool dimensions are harmless to share; there is nothing sensitive here to protect.

FAQ

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Pool Volume Calculator — gallons, liters & cubic meters for any pool shape

Pool water volume

Maintenance reference

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Pool Volume Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Dose chlorine for a season opening

Estimate the water bill for filling a new pool

Size a pool heater before buying

Plan a backyard water feature or koi pond

Convert a European pool spec to gallons

Common pitfalls

Privacy

FAQ

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